Cooperative behavior

The sharpness of the transition in pure lipid preparations shows that the phase change is a cooperative behavior. This is to say that the behavior of one or a few molecules affects the behavior of many other molecules in the vicinity. The sharpness of the transition then reflects the number of molecules that are acting in concert. Sharp transitions involve large numbers of molecules all melting together. 

Radioligand Binding to Receptor Dimers Demonstrating Cooperative Behavior... 

The theory of linked functions establishes the general thermodynamic meaning of the cooperative behavior of the system. On the basis of Hill s equation,... 

In summary, the cooperative behavior of the two metal ions determines the dioxygen chemistry of group 2 bis-Co porphyrins and certain flexible group 1 analogs (e.g., a... 

The model most often invoked to rationalize cooperative behavior is the MWC (Monod-Wyman-Changeaux), or concerted, model. This model is 1.5 times more complicated than the Michaelis-Menten model and took three people to develop instead of two. Most texts describe it in detail. In the absence of substrate, the enzyme has a low affinity for substrate. The MWC folks say that the enzyme is in a T (for tense or taut) state in the absence of substrate. Coexisting with this low-affinity T state is another conformation of the enzyme, the R (for relaxed) state, that has a higher affinity for substrate. The T and R states coexist in the absence of substrate, but there s much more of the T state than the R. This has always seemed backward, since one would expect the enzyme to be more tense in the presence of substrates when some work is actually required. In keeping with the tradition of biochemistry, the MWC folks obviously wanted this to be backward too (Fig. 8-8). 

The limiting cases are limvo 0 a = 1 and limy. x a = 0. To evaluate the saturation matrix we restrict each element to a well-defined interval, specified in the following way As for most biochemical rate laws na nt 1, the saturation parameter of substrates usually takes a value between zero and unity that determines the degree of saturation of the respective reaction. In the case of cooperative behavior with a Hill coefficient = = ,> 1, the saturation parameter is restricted to the interval [0, n] and, analogously, to the interval [0, n] for inhibitory interaction with na = 0 and n = , > 1. Note that the sigmoidality of the rate equation is not specifically taken into account, rather the intervals for hyperbolic and sigmoidal functions overlap. 

In order for an equilibrium to exist between E -E S and ES, the rate constant kp would have to be much smaller than k i However, for the majority of enzyme activities, this assumption is unlikely to hold true. Nevertheless, the rapid equilibrium approach remains a most useful tool since equations thereby derived often have the same form as those derived by more correct steady-state approaches (see later), and although steady-state analyses of very complex systems (such as those displaying cooperative behavior) are almost impossibly complicated, rapid equilibrium assumptions facilitate relatively straightforward derivations of equations in such cases. 

From the experimental BI one cannot distinguish between the three systems a, b, and c. (Note, however, that other properties of the system, such as the pressure, energy, entropy, etc., are different.) This fact could, in some cases, lead to misinterpretation of the cooperative behavior of the system. If kg, S defined in Eq. (4.4.14) must be smaller than unity. This follows from the identity... 

In Section 3.5 we discussed the phenomenon of spurious cooperativity in single-site systems. Since cooperativity, as defined in this book, is undefinable for single-site systems, any apparent cooperative behavior must be due to the presence of different and independent sites. In Section 4.4 we encounter the same phenomenon in two-site systems with different sites. This was shown to be equivalent to the system in Section 3.5. 

Glycine A-methyltransferase is also reported to have an ordered binding mechanism with SAM binding first to the enzyme, there being no metal-ion dependency. Cooperative behavior is observed with SAM binding. The cooperative nature can be eliminated by the tryptic hydrolysis of the N-terminal eight amino acid residues. 

Figure 6.2 The single chain of myoglobin (a) and the four chains (two a and two P) of hemoglobin (b). The cooperative behavior of hemoglobin (sigmoid curve), as indicated in the left panel (c), can be seen as an emergent property, resulting from the interaction of the four chains.

Decentralized solutions can come about by a variety of individual motivations self-interest, altruism, social norms or some combination thereof. There are two mistakes to be avoided in trying to explain cooperative behavior. The crudest is to believe that there exists one privileged motivation - self-interest, for instance - that explains all instances of cooperation. A more subtle error is to believe that each instance of cooperation can be explained by one motivation. In reality, cooperation occurs when and because different motivations reinforce each other. 

When crystals of UP are photolyzed at low temperature to conversions greater than about 0.06%, the IR spectra show numerous v3 bands that are not observed after less extensive photolysis. The onset of this conversion threshold is sharp, suggesting cooperative behavior of several defects. The shift of these bands to high frequency suggests the influence of stress fields... 

Buckingham theory and, 330 chain decomposition, 325 cooperative behavior of defects, 338 deuterium shifts, 361 dispersive interactions, 330 elastic strain, 333 electrostatic coupling, 352 exchange of positions, 351 heteroisotopic pairs, 348... 

The fourth part included a paper by Graham on the onset of cooperative behavior in nonequilibrium states. Suzuki talked about the theory of instability, with special regard to nonlinear Brownian motion and the formation of macroscopic order, and P. W. Anderson developed a series of interesting considerations of very general nature around the question Can broken symmetry occur in driven systems ... 

Interestingly, the propensity of the boron atom to engage in secondary interactions was also examined by Jacobsen. The interaction of the rhodium complex 60 with a model substrate, namely 5-hexen-l-amine, was monitored by 1H NMR spectroscopy.62 The stronger upheld shifts of the alkene resonances compared to those observed upon coordination of the same substrate to the related boron-free salt [Rh(cod)(DIOP)][ClC>4] (cod = cycloocta-1,5-diene) were attributed to a cooperative behavior of the boron and metal centers of 60 that concomitantly interact with the nitrogen atom and alkene moiety, respectively (Figure 20). 

Bremel, R. D., Murray, J. M., and Weber, A. (1972). Cooperative behavior in actin. Cold Spring Harbor Symp. Quant. Biol. 37, 267-275. 

The value A Ef = —35.6 mV has the particular interest of corresponding to a 50 % of character E e-E c and E2c At the average formal potential Ef, the intermediate species reaches half of its maximum value and, hence, at this A Ef species 02 may or may not gain a second electron (and as a direct consequence, for higher AEf it will be considered that the intermediate species is no more stable at the average formal potential). So, this AEf could be considered as the boundary between anti-cooperative and cooperative behavior of both electron transfer reactions [35, 43]. Indeed, it is well known that the voltamogram of an EE mechanism under these conditions is identical to that of an E mechanism multiplied by a factor... 

At present, the interaction between these systems tj — rjmax is occurring at a rapid pace, and therefore individual components of vector H can be attributed to the class of cooperative behavior. Since the present socio-economic structure of the world is presented by all the states in the world, we shall consider a country as a functional element of system H. The r](t) function reflects the result of the interaction of countries both with each other and with nature. Let us describe the sum of the results of their interaction by the matrix B = Z>y, each element of which has a meaning of its own ... 

Dukerich JM, Golden BR, Shortell SM. 2002. Beauty is in the eye of the beholder The impact of organizational identification, identity, and image on the cooperative behaviors of physicians. Admin Sci Q47 507. 

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